The difference between Dolby Atmos and Dolby Digital sound is not what you think

It almost goes without saying that the upgrade that transforms a smart TV into a home theater is its sound system. While the internal speakers on TVs have improved considerably just in the past decade -- they're just fine for news or late-night shows -- simply adding a 2.0-channel soundbar can produce a quantum leap. I almost wouldn't want to watch Dune (the Lynch or Villeneuve movies) without one.

When you're shopping, you'll see the Dolby Atmos label tossed around as one of the most important audio specs. But is it really that special? Should you care about the gaps between Atmos and Dolby Digital, which is widespread at this point? Hopefully, this quick primer should point you in the right direction, whatever your budget.

Dolby Digital vs. Dolby Atmos: The essentials

The workhorse and the cutting edge

Dolby Digital has been around for quite a while -- it dates back to 1992, and the first theatrical release with it was Batman Returns. It's sometimes known as AC-3, and was a considerable leap forward from the various flavors of Dolby Surround that preceded it.

The foremost advancement was the adoption of the 5.1-channel arrangement we take for granted: left, center, and right channels in the front, two rear satellites, and a subwoofer. Naturally, you don't need a full setup to experience Digital. You can drop the subwoofer, for example, or simply listen in stereo. In fact compatibility-wise, the standard is omnipresent. You'll find it on broadcast, satellite, cable, and antenna TV, as well as Blu-ray, DVD, and even LaserDisc. It's also on game consoles and computers.

You can potentially scale the vanilla version of Digital up to 7.1 channels, adding two side satellites, but the preferable route for that is Digital Plus. It can handle 7.1 systems without question, and is pretty much the go-to for streaming services, Blu-ray, and higher-quality broadcast TV.

So why would you need Atmos if 5.1- and 7.1-channel systems are still expensive when you opt for the high end? The answer is sound separation. Through to Digital Plus, all surround sound standards -- including those from DTS -- have involved panning parts of the audio mix across different channels. This can be impressive, but strictly speaking, your audio gear isn't positioning effects with maximum precision. A gunshot that's meant to sound like it's coming from camera right could be pushed to multiple channels instead of your side satellite.

Atmos is a spatial audio format. What that means is that engineers and producers can position individual sound "objects" in 3D space. Positioning is limited only by the number of channels your system has. Indeed, it's important to emphasize the 3D aspect -- if you've got ceiling satellites, or floor speakers that can bounce sounds upwards, you'll hear effects soaring overhead. There are some truly wild Atmos configurations if you've got an unlimited budget, such as 9.1.4 -- nine ground channels, a subwoofer, and four ceiling satellites.

An important note here is that there isn't necessarily a fidelity difference between Atmos and Digital/Digital Plus. Both standards are most commonly served in compressed form, which sounds good enough, and will work with most wired and wireless connections. For lossless, you need to pair one of these standards with Dolby TrueHD, and that's effectively non-existent beyond Blu-ray. The issue is that pairing lossless Atmos with 4K HDR video consumes a tremendous amount of bandwidth, and you can't necessarily count on that for streaming conditions. Honestly, I find it hard or impossible to distinguish between lossless and high-bitrate compression.

The cost is higher than you might think

This is, of course, a highly subjective question unless money is no object. If you didn't think twice about dropping $2,000 or $3,000 on your TV, you probably have the budget for an Atmos-capable soundbar, at the least.

It's worth remembering that the costs of an Atmos system can escalate quickly. The better Atmos soundbars (ones with upfiring drivers) are upwards of $500, and maintaining that quality over separate speakers is going to push the pricetag higher still. Over a certain quantity of speakers, you'll also need a receiver (and possibly pre-amps) to handle all the power and processing demands. You should add a receiver to your cart automatically if you insist on ceiling satellites.

As if that weren't bad enough, most streaming services paywall Atmos behind their most expensive tiers. That means that a service that cost $120 per year might jump to well over $300. Given how fractured content has become between platforms, it's not inconceivable that you might have to set aside several hundred dollars extra per year if you want to hear Atmos everywhere, all the time.

Remember also that a lot of movies and shows predate Dolby Digital, never mind anything later. Their soundtracks weren't mixed with these formats in mind, and it's not like people watching Raiders of the Lost Ark at home in the 1980s were bemoaning the absence of Indy's whip cracking overhead. You''ll enjoy the movie as much with a 2.0-channel soundbar as you will a 7.1-channel Atmos kit.